Chromatographic column

ABSTRACT

A chromatographic column is manufactured in the form of a tube having a core of uniform cross-section which contacts the tube wall at two or more points forming separate longitudinal passages in the column. The cross-section of the core can be polygonal or star-shaped and the core can be drawn into the tube by means of a draw-wire. The core surface constitutes, or is coated with, a partitioning agent and the surface can be roughened. The core and tube can be made of stainless steel or thermoplastics.

UnitedStates Patent 9] Bergen et al.

May 29, 1973 CHROMATOGRAPHIC COLUMN Inventors: Stephen Archbold Bergen; Hanniel Elidad Dubsky, both of Cambridge, England Assignee: Pye Limited, Cambridge, England Filed: Jan. 23, 1970 Appl. No.: 5,261

Foreign Application Priority Data Jan. 23, 1969 Great Britain ..3,936/69 US. Cl ..55/386 Int Cl. ..,.B0ld 15/08 Field of Search....; .;..2.lO/3 l 198; 55/67,

[56] References Cited UNITED STATES PATENTS 2,920,478 l/l960 Golay ..55/l97 3,038,326 6/1962 DeFord 55/l97 Primary Examiner-John Adee AttorneyFrank R. Trifari [57] ABSTRACT 6 Claims, 1 Drawing Figure PAH-INTE M29 I975 v 3 73 5 O INVENTORJ STEPHEN A. BERGEN HANNIEL E. DUBSKY AG NT CHROMATOGRAPHIC COLUM The present invention relates to columns for use in chromatography.

In British Pat. specification No. 937,074, there is described a column comprising a tube of narrow bore which houses a core or filament upon which a stationary phase is coated, and in British Pat. specification No. 1,019,801 there. are described methods of coating the core or filament with a stationary phase and of mounting the core or filament within the tube. Although such columns possess substantial advantages over prior art non-cored columns of narrow bore, for example an increased area of stationary phase per unit length of column and a decreased carrier dead volume, unless the core is accurately centrally positioned a non-uniform carrier flow distribution can result, leading to poor sample resolution.

According to the present invention there is provided a chromatographic column having an elongate passage of substantially uniform cross-section and a core of substantially uniform cross-section situated in said elongate passage, the cross-section of said core being such that it contacts the wall of said elongate passage at a plurality of points to form a plurality of substantially separate passages which extend along said elongate passage, the surface of said core constituting, or being coated with, at least in part, a partitioning agent.

The core is preferably of square cross-section but can alternatively be of other cross-section, e.g., triangular, pentagonal or star-shaped.

The core can be a wire of the desired cross-section and of a material such as stainless steel, as can the tube, although other materials, such as thermoplastics, can be employed for both the tube. and core.

The core surface is preferably roughened, by either mechanical or chemical means, to provide a greater surface area for interchange than would otherwise be the case, and particularly to facilitate coating with a stationary phase material.

The internal diameter of the tube is preferably between 0.5 and 1.02 millimeters with the core dimensions chosen to make the core an interference fit within the tube.

According to another aspect, the invention provides a method of manufacturing a partitioning column for chromatography, including the steps of inserting into an elongate passage of substantially uniform crosssection a core of substantially uniform cross-section such that the cross-section of said core contacts the wall of said elongate passage at a plurality of points thereby forming a corresponding plurality of substantially separate passages extending along said column. The core can be drawn into the tube by means of a draw-wire, of smaller diameter than the tube, which is attached to one end of the core. The surface of the core is preferably roughened and coated with a stationary phase material.

The FIGURE illustrates a cross section of the column and core.

In a preferred form of the invention a column for use in gas chromatography, as shown in the drawing, comprises a tube 1 of stainless steel, with an internal diameter of 0.609 mm containing a core 2 of stainless steel wire of square section-of side 0.406 mm. The diagonal dimension of the wire section is'slightly greater than the internal diameter of the tube and the core, therefore, is an interference fit within the tube.

The surface of the core is coated with a suitable stationary phase 3, for example, squalane. To increase the surface area available for interchange, before being coated the core surface is roughened by sand or metal blasting or etching. The increased surface area obtained this way can be three times or more that of the wire surface when smooth. The roughened surface enables a more uniform coating of stationary phase to be applied to the core and avoids a fall of efficiency due to surface tension of the stationary phase causing formation of drops and leaving certain areas uncoated. It also enables a larger volume of stationary phase mate rial to be employed without an increase in the thickness of the stationary phase coating. Another advantage obtained by roughening the surface of the core is that the core may be treated with an active substance of the type normally used as a stationary phase in packed columns, e.g., graphite, porapak, or silicagel.

A column of the form shown is manufactured by first roughening the surface of the core wire 2, coating it with a suitable stationary phase material 3 according to known techniques, attaching a draw-wire of smaller diameter than the bore of the tube 1 to one end of the core 2 and passing the draw-wire through the tube. The core wire 1 is then drawn through the tube 2 to make an interference fit therein.

Although a column having a square section core has been described, cores of other section can be employed. However, it has been found that a core of square section presents an effective compromise between conflicting requirements of minimization of column dead volume and maximization of surface area available for interchange.

What we claim is:

1. A chromatographic column having an elongate tubular passage of substantially uniform cross-section and a core of substantially uniform cross-section situated in said elongate passage, the cross-section of said core being such that it contacts the wall of said elongate passage at a plurality of points to form a plurality of substantially separate passages which extend along said elongate passage, said passage and said core having dimensions making the core an interference fit within said passage, the surface of said core constituting, at least in part, a partitioning agent.

2. A chromatographic column according to claim 1 in which the cross-section of said core is a square and the cross-section of said elongate passage is substantially circular.

3. A chromatographic column according to claim 1 in which said core is a stainless steel wire.

4. A chromatographic column according to claim 1 in which said elongate passage is formed by an elongate stainless steel tube.

5..A chromatographic column according to claim 1 in which the surface of said core has been roughened so as to increase substantially the surface area at which a partitioning interchange can take place with a fluid medium when said medium is passed through said column.

6. A chromatographic column according to claim 1 in which the cross-section of said elongate passage is substantially circular with an internal diameter which is not less than 0.5 millimeters and not more than 1.02

millimeters.

I I III l 

1. A chromatographic column having an elongate tubular passage of substantially uniform cross-section and a core of substantially uniform cross-section situated in said elongate passage, the cross-section of said core being such that it contacts the wall of said elongate passage at a plurality of points to form a plurality of substantially separate passages which extend along said elongate passage, said passage and said core having dimensions making the core an interference fit within said passage, the surface of said core constituting, at least in part, a partitioning agent.
 2. A chromatographic column according to claim 1 in which the cross-section of said core is a square and the cross-section of said elongate passage is substantially circular.
 3. A chromatographic column according to claim 1 in which said core is a stainless steel wire.
 4. A chromatographic column according to claim 1 in which said elongate passage is formed by an elongate stainless steel tube.
 5. A chromatographic column according to claim 1 in which the surface of said core has been roughened so as to increase substantially the surface area at which a partitioning interchange can take place with a fluid medium when said medium is passed through said column.
 6. A chromatographic column according to claim 1 in which the cross-section of said elongate passage is substantially circular with an internal diameter which is not less than 0.5 millimeters and not more than 1.02 millimeters. 